The present invention relates to multicylinder internal-combustion engines of the type comprising:
at least one intake valve and at least one exhaust valve for each cylinder, each valve being provided with respective elastic return means, which push the valve towards a closed position for controlling respective intake and exhaust pipes; and
at least one camshaft, for activating the intake and exhaust valves of the engine cylinders by means of respective tappets;
in which each intake valve is controlled by the respective tappet against the action of the aforesaid elastic return means by interposition of hydraulic means that include a pressurized fluid chamber;
said pressurized fluid chamber being designed to be connected by means of a solenoid valve to an exhaust channel in order to uncouple the valve from the respective tappet and bring about fast closing of the valve as a result of the respective elastic return means;
electronic control means for controlling each solenoid valve so as to vary the time and the opening stroke of the respective intake valve according to one or more operating parameters of the engine;
in which the hydraulic control means for controlling the intake valves of the engine and the solenoid valves associated thereto form part of a pre-assembled unit mounted on the engine cylinder head.
An engine of the type specified above is, for example, described and illustrated in the European patent application EP-A-0 803 642 in the name of the present applicant.
The purpose of the present invention is to further improve the device described above.
With a view to achieving the above purpose, the subject of the present invention is a multicylinder engine having all the aforementioned characteristics and further comprising the characteristics that form the subject of the characterizing part of the annexed claim 1.